Treatment of artificial materials



Patented May 12, 1942 TREATMENT or anrmcmr. MA'rEarALs David ,JamesHadley, Banstead, Surrey, -and Thomas Jackson, Spondon, near Derby,England, assignors to Celanese Corporation of America, a corporation ofDelaware No Drawing. Original application May 8, 1940,

Serial No. 333,936. Divided and this application December 27, 1940,Serial No. 372,005. In

Great Britain May 23, 1939 2 Claims.

This invention relates to the treatment of artiflcial materials, andmore particularly to processes for improving the properties, especiallythe extensibility, of artificial filaments, threads, yams, fabrics,ribbons and the like made of or containing an organic derivative ofcellulose. This application is a divisional of our application S. No.333.936, filed May 8, 1940.

It is known that it is a matter of considerable importance to weaving,knitting, twisting and other textile operations that filaments, threads,

yarns, and like'materials should have a substantial extensibility,preferably an extensibility of 10 to 12 or 15% or more. It has beendisclosed in US. Patent No. 2,058,422 that the treatment of artificialmaterials having a basis of an organic derivative of cellulosewithorganic solvents, swelling agents' or latent solvents, in theabsence of tension suflicient to stretch the materials, serves toincrease their extensibility. The selectionof the agents to be employedin this process is a matter of great importance and is determined by anumber of factors involving elaborate research. The most importantconsideration, which weighs very heavily with the manufacturer, is thatof reproducibility or control of results, and this is a particularlyimportant matter when dealing with textile fabrics and L like materials,since quite small variations in physical characteristics, as ciallyextensibility, occurring over the leng"th* =o such materials are thefilaments or other materials are under no tension or under only a slighttension so that they are substantially free to shrink under theinfluence of the treatment agent. It the agents are applied while thematerials are under relatively high tension, the tension shouldsubsequently be reduced or removed so that the materials are allowed toshrink while still under the influence oithe agents.

The treatment agent maybe employed alone or in admixture with othersuitable agents, e. g.

the lower alkyl formates or methyl acetate. Suitable diluents are, forexample, glycol, glycerol and other hyd'roxy compounds which aresubstantially without action on the materials. Preferably,. however,water-immiscible liquids are used as diluents, examples of which arebenzene, toluene, xylene and other cyclic hydrocarbons, benzine,petroleum ether, kerosene and'other aliphatic hydrocarbons, carbontetrachloride, perchlorethylene and other chlorinated or halogenshownupvery clearly in" fabrics formed there from, e. g. by the faults whicharise from uneven tension duringthe fabric-forming operation.

The over-all efilciency of the agents, their tox-' icity, and economicfactors generally also come into consideration.

We have now found that propylene chloride ated compounds which are inertor substantially inert'towards the cellulose derivatives. Again,relatively high boiling diluents, e. g. tetrahydronaphthalene anddecahydronaphthalene, may be employed. It will be understood, however,;that in general, diluents are not employed with the propylene chloride.I The concentration in which the treatment agent is employed and thetemperature of workingwill depend upon the particular cellulosederivative which is present in the filaments or other materials to betreated, upon the physical characteristics of those materials and uponthe degree of modification of the physical characteristics which isdesired. Preferably, the shrinkage eiiected does not exceed about 20 or25% and it is generallymost advantageous to efiect a shrinkage of 10 to15%'. Shrinkage may be restricted by suitably modifying the treatmentmedium, as regards composition, concentration and/or temperature, and/orby treating the materials while they areunder sufiicient tension toprevent more than the desired shrinkage, the

the process with any particular materials, provided, of course, that thetemperature of treatof cellulose are subjected, in the absence oftension sufilcientto stretch them, to the action of propylene chloride,v

Preferab' the treatment is carried out while like made of or containingan organic derivative f 'sion with a medium consisting of tension beingmaintained so long as the materials remain under the influence of thetreatment agent.

When treating materials having a basis of acetone-soluble celluloseacetate, 'it is found that a satisfactory increase in extensibility canbe secured by treating them in the absence of tenpure propylene chlorideat about -78 C. I

The treatment agent according totheinvention may be employed in any ofthe methods described, for example, in U. S. Patents Nos. 2,070,583 and2,058,422. The invention is of the greatest importance when applied tofilaments, threads, yarns, fabrics, ribbons and the like containing orderived from high tenacity wet-spun materials or materials which havebeen stretched to 200% or more of their original length in hot water orwet steam or in a medium containing an organic solvent or swellingagent. It will be understood, however, that the: invention is notlimited to the treatment of these materials, but is applicable generallyto organic derivative of cellulose materials the extensibility of whichit is desired to increase. It has further been found that the treatmentagent according to the present invention imparts to staple fibres,particularly such as have been formed by cutting operations, a crinkledor crimped effect, which greatly enhances their spinning qualities.

'Reference ha been made above to materials having a basis ofacetone-soluble cellulose acetate and the invention is of the greatestimportance in connection with the treatment of such materials. However,materials made from other cellulose acetates or other esters ofcellulose such as, for example, cellulose formate, propionate andbutyrate, and mixed esters, e. g. cellulose acetopropionate andacetobutyrate, and also from celluloseethers, e. g. methyl, ethyl andbenzyl cellulose, 'or from cellulose ether-esters, may be treated.

The following example illustrates the invention: 7

Example Dryspun cellulose acetate yarn, which has been stretched in wetsteam to 1000% of its original length, is immersed for ten minutes at 76C. in hank form in a bath of propylene chloride and allowed to shrinkfreely. The yarn is then washed with a low-boiling petroleum ether anddried in a current of warm air. The product is found to be uniformlyshrunk and to have an improved extensibility.

Having described our invention, what we desire to secure by LettersPatent is:

1. Process for increasing the extensibility of artificial filamentarymaterials made of or containing an organic derivative of cellulose,which comprises subjecting such filamentary materials which have beenstretched in the presence of wet steam to 1000% of their original lengthto increase their tenacity, to immersion for ten minutes at 76 C. in abath consisting solely of propylene chloride, in the absence of tensionsufficient to stretch said filamentary materials,

is increased.

2. Process for increasing the extensibility of artificial filamentarymaterials made of or containing cellulose acetate, which comprises subjecting such filamentary materials which have been stretched in thepresence of wet steam to 1000% of their original length to increasetheir tenacity, to immersion for ten minutes at 76 C.

in a bath consisting solely of propylene chloride,

DAVID JAMES HADLEY. THOMAS JACKSON.

